A substrate processing apparatus, in which a substrate, i.e., a semiconductor wafer, is subjected to a plasma processing, includes: a chamber for accommodating the wafer therein and being capable of lowering the pressure inside the chamber; a susceptor (mounting table) arranged at a lower portion of the chamber; and a shower head arranged to face the mounting table in the chamber. The wafer is mounted on the susceptor which is connected to a high frequency power supply to serve as an electrode for supplying a high frequency power to the chamber. The shower head through which a processing gas is supplied to the chamber is grounded to serve as a ground electrode. In the substrate processing apparatus, the processing gas supplied to the chamber is excited by the high frequency power to generate a plasma and the wafer is subjected to the plasma processing by the plasma.
Meanwhile, a susceptor of a conventional substrate processing apparatus has been developed to be movable in order to make adequate distribution of the plasma in the chamber, especially, a space between the shower head and the susceptor. In the substrate processing apparatus, the susceptor is movably configured to adjust a width (hereinafter, referred to as a gap) of the space between the shower head and the susceptor. Moreover, a substrate processing apparatus including a movable shower head, instead of the movable susceptor, has recently been suggested to overcome the layout restriction on peripheral parts of the conventional substrate processing apparatus.
FIG. 4 is a schematic cross sectional view showing a structure of a substrate processing apparatus 100 including a movable shower head 103.
In the substrate processing apparatus 100 shown in FIG. 4, the shower head 103, which is arranged to face a susceptor 102 inside a cylindrical chamber 101, is of a substantially circular plate shape having an outer diameter that is substantially identical with an inner diameter of the chamber 101. The shower head 103 is upwardly and downwardly moved along an inner wall of the chamber 101 by a lifting unit (not shown) like a piston. In FIG. 4, the shower head 103 placed at a lowermost position and that at an uppermost position are shown in a solid line and a dotted line, respectively.
The shower head 103 includes: a processing gas introduction system having a gas flow path 104, a buffer chamber 105, and gas holes 106; and a gas supply line 107 connected to a gas supply source (not shown) for supplying a processing gas from an outside to the processing gas introduction system. As described above, since the shower head 103 is upwardly and downwardly moved while the gas supply source is typically fixed, it is necessary that the gas supply pipe 107 be bendable to follow the upward and downward movement of the shower head 103.
Typically, a flexible tube is known as a supply pipe for supplying a fluid from a fixed fluid supply source to a movable structure. In a space simulator, for example, the flexible tube is employed as a flexible insulating line for supplying liquid nitrogen from a vacuum vessel to a shroud of a movable door. (see, e.g., Japanese Patent Laid-open publication No. 2003-137200)
However, as shown in FIG. 5, since a flexible tube 108 is formed of a thin wavy metal pipe 109 fabricated by a drawing process and a metal mesh blade 110 covering a peripheral portion of the metal pipe 109, the flexible tube 108 has a relatively low flexibility and a relatively high stiffness against bending. Accordingly, when the flexible tube 108 is extensively bent, a high stress is easily generated. Moreover, when the flexible tube 108 is applied to a structure that is movable by a large displacement, it is likely that the flexible tube 108 can be broken early to thereby shorten its life span. As a result, it is difficult to apply the flexible tube 108 to the shower head 103 that is frequently vertically movable by a large displacement of 70 mm.
For that reason, as shown in FIG. 6, it has been suggested to employ a bellows 113 connected to a gas receiving part 111 joined to the shower head 103 and a fixed gas supply source 112 separated from the substrate processing apparatus 100.
The bellows 113 is made of only a metal pipe in which a plurality of ring-shaped members (hereinafter, referred to pieces) having mountain shaped cross sections are connected to one another. Accordingly, the bellows 113 has a relatively high flexibility and a relatively low stiffness against bending. Therefore, even though the bellows 113 is applied to the shower head 103 that is frequently extensibly displaceable, no high stress is generated in the bellows 113 and thus the flexible tube 108 is not broken early to thereby shorten its life span.
However, even nano-sized particles cannot be allowed to be present in the chamber 101 of the substrate processing apparatus 100. Accordingly, it is necessary to reduce the particle generation probability as low as possible.
In the bellows 113, each of the pieces is fabricated by welding two metal rings. When the bellows 113 is bent, the relative positions of the two metal rings of each of the pieces are changed. Accordingly, particles are easily generated. The generated particles may be introduced into the processing gas introduction system of the shower head 103 through the bellows 113. Specially, as the bellows 113 is longer, the particle generation probability gets greater.
Moreover, the bellows 113 may droop extensively due to the high flexibility for bending. The extensively drooping bellows 113 may also be interfered with other structures of the substrate processing apparatus 100. Accordingly, it is necessary to provide a guide for controlling the droop, thereby lowering the freedom of arrangement.